...like yourself I've taken tens of thousands (indeed at about 70% keeper rate) with various EF longer lenses and 7d, but this is simply NOT possible to repeat with N7; there was a very similar thread recently (and about much less ambitious moving target) 55-210 and its inablity to trace advancing walker

jpr2

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A 55-210 lens at 210mm and ISO 800 and the shooter complains of mushy eyes at 100% crop.